1. Field of the Disclosure
The present disclosure generally relates to patient monitoring devices and more specifically, embodiments of the present disclosure relate to cables connecting a monitor and a sensor of the patient monitoring device.
2. Description of the Related Art
Physiological measurement systems using spectroscopic analysis are a widely accepted noninvasive procedure for measuring patient characteristics such as oxygen and glucose levels. Measuring these characteristics is important for patient wellness because for instance, an insufficient supply of oxygen can result in brain damage and death in a matter of minutes. Thus, early detection of low blood oxygen level is of crucial importance in the medical field, especially in critical care and surgical applications. Patient monitors commercially available from Masimo Corporation of Irvine Calif., USA, measure many physiological parameters including oxygen saturation, pulse rate, perfusion, carboxyhemoglobin, methemoglobin, total hemoglobin, glucose, overall wellness, respiration, combinations of the same and others.
As shown in FIGS. 1A and 1B, a physiological measurement system consists of a monitor 101, a noninvasive optical sensor 115 applied to a patient, and a cable 111 connecting the sensor and the monitor. The system is controlled using input keys. The monitor 101 may be a portable standalone device or may be incorporated as a module or built-in portion of a multiparameter patient monitoring system. The monitor displays measurements of various physiological patient characteristics on a display 105, which may include an oxygen saturation level, a pulse rate, and an audible indication of each pulse via a speaker 107. In addition, the monitor 101 may display the patient's plethysmograph, which is a visual display of the patient's pulse contour and pulse rate, as well as a myriad of other measurements and calculated parameters.
To perform the above functions, the monitor 101 energizes one or more emitters in the sensor 115 that irradiate tissue under observation, such as, for example, a finger, toe, foot, hand, ear, forehead or the like. The radiation from the emitters is scattered and absorbed by the tissue such that some attenuated amount emerges and is detected through one or more detectors located in the sensor 115. The detector(s) produces one or more signal(s) indicative of the intensity of the detected attenuated radiation and forward the signal(s) to the patient monitor 101 for processing. The sensor 115 that houses the emitters and the detectors can be disposable, reusable, or partially reusable and disposable. Reusable sensor may include a clothespin-shaped housing that includes a contoured bed conforming generally to the shape of a finger. The emitter and detector signals are transmitted over the cable 111 connecting the monitor and the sensor.
Depending on the nature of cables and the signals that are transmitted through cables, cables can be affected by a phenomenon known as crosstalk. Crosstalk occurs when energy from one signal interferes with another signal. Such interference can cause significant distortion in the transmission of information which can lead to incorrect measurements in physiological monitoring applications. As the cable 111 often communicates high voltage emitter driving signals and low voltage sensitive detector signals, the cable 111 may unfortunately cause unwanted interference on the sensitive detector signals used to determine measurements of the physiological parameters.